Expanding point bullet



Nov. 17, 1964 BURNS, JR 3,157,137

EXPANDING POINT BULLET Filed April 1, 1963 2 Sheets-Sheet 1 Figz INVENTOR} 4 ART/{UP M Ewe/v5, (/19. BY

1 5\ W MBA 5y Nov. 17, 1964 A. H. BURNS, JR

EXPANDING POINT BULLET 2 Sheets-Sheet 2 Filed April 1, 1963 INVENTOR. ARTHUR fffio/eA/s', JR.

A 77 ORNE Y United States Patent 3,157,137 EXPANDING PtllNT BULLET Arthur H. Burns, 31:, Qheshire, Conn, assignor to )lin Mathieson Chemical Qorporation, a corporation of Virginia Filed Apr. 1, 1963, Ser. No. 269,280

10 Claims. (Cl. 102-91) This invention relates to projectiles and more specifically to an improvement in projectiles of the expanding type known as mushrooming bullets, and to the method of their fabrication.

Bullets having an expanding point generally consist of a core of soft malleable material such as lead or a lead alloy and a relatively hard jacket, usually a copper base alloy, capable of resisting stripping from the core while taking not only the rifling action of the gun but also the mushrooming action of penetration of the target.

Jacketed bullets of this type include various bullet designs such as the soft-point bullets having a rounded nose of core material, and the more sharply pointed bullets having higher ballistic performance at the longest range. One such sharply pointed bullet is the hollow point bullet having a portion of the core exposed but recessed within the jacket at the nose. Another has a jacket extending over the ogivally pointed nose with modifications in the jacket to enable deformation at the nose.

Heretofore, various modifications have been made in this general jacketed bullet construction in order to improve the expansion characteristics of this type of bullet. According to one modification, metal is removed from the interior of the base jacket to provide it with longitudinally extending cuts or slits partially through it at the mouth. This arrangement has been tried with or without a tip jacket. The cuts have been extended all the way through to indent the edge and provide spaced petals or serrations at the mouth of the base jacket. Such projectiles have also been constructed with a recess of one type or another in the lead core at the point. According-to other and more complicated modifications, holes have been pierced from one side of the point to the other, separate anvil pieces have been embedded in the point, and corrugations have been tried in the tip jacket.

How the objects and advantages of this invention are obtained will become apparent from a general discussion together with a description of specific embodiments shown in the drawing in which:

FIG. 1 is a front view of one embodiment of the pro jectile according to this invention, shown enlarged;

FIG. 2 is an elevational cross sectional view of the embodiment of FIG. l taken on line 11-11, and shown partly in section, with the same enlargement;

' FIG. 3 is another front view of a still further preferred embodiment, similarly enlarged, of only the tip;

FIG. 4 is an'elevational side view in longitudinal cross section showing a die apparatus with a preliminary assembly positioned therein for an intermediate manufacturing operation for making a bullet of this invention; 7

FIG. 5 is an end view taken on line V-V looking down upon the assembly of FIG. 4 after completion of the operation shown; and

FIG. 6 is an elevational side view showing a point shaping die in cross section and the substantially completed bullet positioned in the dieand formed therein completed adjacent the nose.

In accordance with this invention, there is provided ity to uniform and full inward ribbing sometimes accompanied by partial splitting along predetermined lines while at the same time offering yielding but firm support to the expanding core with a scoop-like unfolding structure to avoid excessive core fragmentation and separation. This is done without cutting away and removing any part of the much needed jacket support to give a significant improvement in uniformity of mushrooming, par ticularly at maximum ranges, i.e. at the lowest velocities. In an uncomplicated and economical way, the uni form expansion characteristics of this type of bullet are further extended so that the bullet behavior even at very low velocities has a remarkable uniformity which is comparable with that obtained at other ranges and velocities including the closest range and highest velocity.

The malleable core may be made either from a solid slug or from metal powder, which is compressed to control density and rate of bullet upset.

The improvement is obtained by pinch-pleating the tapering mouth of the base jacket by means of preliminary creasing in such a way as to form a round rim thickened staves and a number of deeply inwardly extending folded webs, each between adjoining staves to form stave-like flanged panels at the edge of the jacket. Each folded web involves one very sharp bend, a single 180 bend, at which the metal is overstressed to have at least a pronounced proclivity to split, and also in volves an internal thickness of web extending radially like spokes from the rim into abutment with adjoining ribs at a hub. Abutment is back of the tip.

The resultant series of ribs and series of nose openings provide a partitioned hollow structure that facilitates bullet penetration with proper mushrooming at the target.

The folded ribs and a like number of staves form an uninterrupted continuation in an abutted array around the circumference at the hollow tip from jacket metal at its mouth originally of substantially uniform thickess circumferentially. Each stave or panel is flanged at its margins; and the staves are abutted at least at their flanges to form a thickened nose rim about thespokes. There is preferably a necking-in and a longitudinal fracture only partially down each rib at the sharp bend an expanding bullet similar to the hollow point type having a core enfolded within a base jacket and having a base jacket constructed with special creasing and swaging at the mouth soias-to achieve at'least a proclivto accomplish a pulling apart and a splitting between the contiguous flanges beginning at the edge of the jacket. Flanged slits preferably are formed in the jacket wall in each rib-but only at the edge. The resulting flanged and abutted stave structure of the jacket edge provides desired tip as well as core support while permitting ex pansion with improved uniformity.

Splitting is achieved by an initial dentingat evenly spaced points and a final severe working inwardly rather than by complete removal of part of the jacket edge or by any complex cutting and stretching operation.

The basejacket, to give further core support, is locked to the soft core by one or more cannelures involving knurls of the type shown in prior US. Patent 1,730,871, which provides an interior portion of the jacket of decreased diameter.

At the mouth of the jacket in the finished bullet, there are preferably six, marginally flanged, longitudinally as well as circumferentially curved staves not only integral with .the rest of the jacket but also at least contiguous, if not integral as well with adjacent staves forming sectors of the hollow tip. Adjoining staves are buttressed and are largely interconnected by a tapering, pinch pleated, nose partition structure providing the greatest marginal flanging back of the edge of the base jacket but tapering to the least flanging at the ends of jacket edge sufficiently to put the resulting evenly spaced ribs in contact around the central axis. The thickness of the base jacket material at the edge, which originally is in the range from about 0.010 of an inch to about from 0.015 of an inch for the small arms ammunition contemplated according to this invention, is uniformly increased at least in the staves by a necking action in forming the ogive. The pleated web, radially, forming the ribs, and the staves together nearly close the hollow tip except for multiple openings at the nose of the fully jacketed bullet.

At very edge of the nose, all the jacket is in the abutted stave ends. Back of the aperture, where the ribs touch, the greater proportion of jacket is in the ribs and the lesser in the staves.

Six creases were found suitable usually for making the rosette hollow tip of this invention; these provide a hexafoil formation of the jacket mouth as shown in FIGURES 1 and 3. In practice the number of staves and pleated webs selected is determined by the jacket thickness, size of jacket mouth openings desired and the extent of bullet nose taper involved to give the necessary flanging, contacting, and hollow nose buttressing by the ribs.

By holding the hardness of the jacket to a minimum, and/or by otherwise varying the metal thickness and degree of infolding at the pleats, it is possible to reduce the sharpness of the bend somewhat and thereby avoid excessive pre-splitting at each reverse bend of the jacket while maintaining a stress concentration predisposing the jacket upon target impact to split uniformly along predetermined lines. This provides a variation in the degree of constraint offered the core making the jacket month more suitable for certain varieties of this type of hollow point bullet. The soft core material provided is insuflicient to fill the jacket final finished to a rosette tip.

Since the jacket mouth openings at the rosette tip can be made very small, powdered core material can be employed as well as the usual solid slug of lead base metal, compressed in the jacket.

When powdered lead is used, the degree of granulation and compression is varied to control the bullet density sought. By adjusting the density nearer that of the jacket, bullet unbalance from jacket thickness variation is minimized.

Because of necking-in of the jacket mouth, i.e. bending in of each stave, the entire edge of the base jacket at the nose is sloped rearwardly with respect to the axis of the bullet to provide an outwardly flared hollow ahead of the ribbed jacket edge including the substantially identically beveled or flattened leading edge of the pleated flange and rib forming webs. The slope is substantially at a right angle to the jacket curvature tangent.

Upon impact this rosette type of hollow tip provides a wedge action on the nose of the bullet to advantageously initiate the outward expansion of the jacket and core in all radial directions uniformly.

In the pleated region about a central opening, there is an abu'tted substantially double flange structure substantially' thicker circumferentially than the greatest radial wall thickness of the adjacent sectors. In this region, the jacket metal is gradually deformed to create a tiny central opening and a circumferential array of as many small openings as there are ribs, extending radially.

In the embodiment of FIGURE 1, the bullet has a base jacket 1 from the relatively flat, open edge 2 of which there recedes a nose hollow '1' formed by abutting ribs extending over the nose portion 21 of the soft core 26. Bordering the nose there is relatively thin jacket portion 3 bearing the substantially full circular annular jacket edge 2 and on the outside of which there are at the apex of tiny cusps at the edge 2 and taper away from it to a hairline.

Each pinch pleat rib 10 consists of a pair of flanges 11 and 12 which are integral extensions of the lateral margins of the staves 9*. These are abutted internally along a line at which the flanges 11 and 12 form ribs 10 which are in contiguity at least adjacent their inner ends at which the flanges may be partially split from each other, however along only a very small part of the length at the inner end 13 of each pinch pleat rib. Therefore the array of alternate ribs and staves form a continuous array of flanged jacket metal staves adjacent the jacket edge 2 and a multiplicity of hollow spaces 14 about a central opening 15, around which ribs 10 abut at 16.

At the edge 2 the thickness of each of the flanges 11 and 12 and thickness of the intervening staves 9 are sub stantially equal to make each internal rib 10 of about twice this thickness and to extend inwardly sufficiently to form a hollow point subdivided into openings 14 and 15. The mouth portion 3 of jacket 1 adjoins the thicker rear part 4 integral with the base 5 of the jacket provided with a knurl 6 forming a circumferential indentation in the thick circular cylindrical part 9 of the base jacket. Remotely from opening 15 and edge 2, each rib 10 becomes not only shallower but its web thicker and less flexed so that splitting by fracture occurs only at 13.

Back of the external hollow 7 and within ribs 10 is an internal hollow 17, forming a space between nose ribs 10 and the core front 21. Thus, the bullet core stress at the nose is reduced. In this embodiment, the open point includes hollows 7 and 17, and ribs 10 making openings 14 and 15 which connect these hollows.

When the bullet of FIGURES 1 and 2 strikes its objective and has achieved substantialpenetration, the flanged staves under rifling-induced rotation are twisted open and bulged outwardly to form curvedscoop-shaped flutes and eventually splitting occurs from the tip all the way back between the flutes as the pleated ribs unfold. Finally continued bulging and the concomitant fracturing is further accompanied by a bending back or rearward furling of the staves 9 which at the heaviest impact will ultimately peel back the relatively thin front end 3 of the jacket until peeling is stopped at the thickened walls of the cylindrical jacket wall 4 adapted to take the rifling of the gun barrel.

In the embodiment having the tip of FIGURE 3, the bullet also comprises a base jacket 1 and a soft core like 20, not shown. Adjacent the front edge 22 of the jacket there is a sharper bullet ogive then shown in FIGURE 2 and a plurality of pinch pleat ribs or spokes 18 which extend inwardly somewhat more deeply than internal ribs 10 and form a series of pronounced splits 23 within the cusps 19 in the jacket wall at the edge of the jacket. In.

the presence of more severe swaging, the apex 23 of each cusp is so severely bent that fracturing does occur more completely. This form of the bullet provides a smaller point by filling up more of the opening at the recesses 24' and 25 and flattening more at both 23 and 26.

In fabrication of the bullet in accordance with this invention, there is followed the procedure of cupping to make cup 101 from desired base jacket metal; assembling with a slug or particles of core material 120 pressed within the jacket cup as shown in the apparatus of FIG- URE 4 after pressing; an edge creasing to provide circumferentially spaced indentations 108 adjacent the open edge of the hollow nose cup-shaped product and swaging the creased assembly of FIGURE 5 to finish the bullet shape at its nose.

The indentations are achieved with a. pie-cut edge creaser shown in FIGURE 4 and having a circumferential array of radial directed fins corresponding in number to the number of pleats desired at the open end of the jacket. This sort of creasing'turns in the open end of the jacket to form a rather frnsto-c'onical shape there having a circumferentially spaced s eries of. edge flutes 109 am ss and cusps 108 at the latter of which the pleated ribs will be formed in the final swaging operation shown in FIG- URE 6. According to the process of this invention there is provided sufiicient inward extension and thickness in the pleated region of the ribs to make a sufficiently severe bend and thereby achieve a predetermined line of preferential splitting without any jacket cutting or difiicult jacket drawing to create grooves, indentations, or scallops.

As shown in FIGURE 4, the cup 101 has a posterior portion of greatest thickness adjacent its closed base and also a tapering anterior portion 103 terminating in the edge 102 of the open end of the cup.

In the cavity of die 30 there is a sea-ting pin 31 upon which there is placed jacket cup 101 containing a compressed slug 120 of core material having a front end recessed adjacent the straight cup edge 102.

Thinness at 103 may be obtainable by a conical flare terminating in an enlarged cylindrical portion adjacent the edge 102. Either of these types will provide a suitable thin front end 103 for making the ogival part 3 of the finished bullet jacket.

The cup is creased with a crimping die 40 having in its cavity 41 six radially arrayed equally spaced creasing fins 42. When the jacket cup edge 102 is thrust into cavity 41 by die pin 41, these fins crease the cup 101 at 108 until there is developed the intermediate foil shaped edge and flutes 109 shown in FIGURE 5. Knockout pin 32 ejects the intermediate product shown there.

The crimped assembly is then subjected to a further operation in a suitable female swaging die 50, the interior contour of which corresponds to the desired finished contour for the projectile at itsnose and along its sides. As plunger 51 moves in during swaging, the circumference of the anterior portion 3 of the jacket 1 is reduced radially and the pleats 8 are formed to make the final finished sharply tapered point at the mouth of the jacket.

As a result of this operation, at this stage parting lines on the exterior of the open point jacket are discernible by the naked eye, inasmuch as they form external indentations in the jacket in the shape of cusps.

In the formation of stave-like sectors 9, the open edge 2 at the front end of the jacket is bent inwardly to slope the edge rearwardly to grip the soft core 20 more snugly. Consequently, the tip of the jacket 1 does protrude beyond the unexposed nose 21.

The expansion action of the structure of this invention appears to be more uniform because of the combination of (a) edge unsupported paneling in the staves and (b) regular, thick and rather deep internal ribbing which notches the core, but not until after impact, which reinforcing the paneling longitudinally, intermediate the ends of the staves, and further in combination with a short core, which may be a compressible compact of coreparticles. This minimizes erratic upsetting of the core all the way up to maximum impact because it gives a preferred variation in the tendency of the jacket to tear ing radially deeper than the rest of the flange to define hollows improves the delaying action.

As the severity of impact is increased, a desired continu ation and increase of resistance is offered because the part of the jacket pleats coming into action becomes shallower but broader so that at each stage the web there will not open initially between the moving staves but will continue to offer confinement to the upsetting core until the required unfolding followed by complete splitting occurs. Wherever the pleated rib is finally split, progress of the split becomes more diflicult as the ribbing tapers away and the degree of metal stressing and hardening at the bend decreases, whereupon the increasing bulk of expanded core material continues to encounter support and guidance as the staves open outwardly and finally furl back with increasing resistance.

This invention is an improvement over expanding bullets made according to US. Nos. 1,062,865; 2,321,344;

2,327,950; 2,765,733; and 2,838,000.

What is claimed is:

1. In an expanding bullet, the combination of a relatively hard metal jacket with a closed base and a nose tapering to a partitioned aperture at the point of the bullet, and a relatively soft metal core in said jacket, said jacket aperture having a substantially circular rim, said core terminating within said jacket to define said hollow point at said aperture, and said jacket at the nose being radially folded inwardly at uniform intervals around and adjacent said aperture to form a plurality of jacket staves each abutting adjacent staves extending from said rim and to form intervening jacket ribs extending longitudinally and radially inwardly between said core and rim from said staves into contiguity with adjacent ribs each at a re-entrant fold in said rib to form at said aperture a central hub and a multiplicity of hollows around said hub.

2. The combination of claim 1 wherein the hollows are distributed substantially uniformly around a central hollow bordered by the folds.

3. The combination of claim 1 wherein the jacket at each fold is fractured radially at a centrally directed apex intermediate the length of each rib.

4. The bullet of claim 1 wherein the core consists of metal particles locked within the aperture by the jacket ribs.

5. The bullet of claim 1 wherein the core consists of metal particles compacted and locked within the jacket.

6. The bullet of claim 5 wherein the core particles include lead base metal compacted to a density substantially that of the jacket whereby the eflects of the slightest eccentricity between said core. and said jacket is miniat regularly spaced intervals with the least initial resistance at the lowest velocities of impact and with the most final resistance at the end of impact at highest velocity.

At the lowest velocities of impact, the finished bullet because of the softness of the core, especially when compressible, and heavy ribbing provides pro-splitting with edge reinforcement and low resistance to upset needed at the very edge of the jacket. The hollow point with the flanged split oflers the least resistance to expansion on account of accordion action while at the same time tottering desired but momentary delay in expansion in the initial circumferential confinement to the expanding core on account of the flanging. Thus, expansion occurs readily even at distant ranges where the energy is considerably spent and the velocity low, but with a sharp hollow tip premature mushroming is avoided to allow sufficient penetration of the bullet tooccur first. The

central edge of the relatively heavy double ribbing be mized.

7. The combination of claim 1 wherein the jacket is thickened at the rim.

8. The combination of claim 1 wherein contiguity oc curs adjacent centrally directed apexes forming a constriction in the hollow point inwardly of the rim.

9. An expanding bullet comprising a relatively hard metal base jacket having a posterior closed at the base, a tapered nose and having a central cavity open at an aperture at the edge of said tapered nose of the jacket, and a soft core partially filling said cavity from the jacket base to a hollow point at said aperture, said core being in engagement with said jacket at least at one area of decreased di ameter in said posterior and terminating short of said edge, said edge defining said aperture comprising with a substantially circular rim about a. central hollow together with circumferentially spaced hollows disposed coaxially about said central hollow, all said hollows being surrounded by ogivally converging jacket staves abutting ad jacent staves to define a laterally closed substantiallycircular exterior cross section of the nose having between adjacent staves an intervening re-entrant fold folded adjacent staves, said rib extending inwardly to define marginal flanges of the adjacent staves and forming said ribs uniformly circumferentially spaced and longitudinally and radially extending between the hollows adjacent said edge, said ribs converging about said central hollow each at an apex in contiguity with adjacent ribs thereat, said circumferentially spaced hollows being each separated from said central hollow by said marginal flanges of a stave also in contiguity with each other.

10. In an expanding bullet, the combination comprising a relatively hard jacket with a closed base and with a nose tapering to a partitioned aperture at the point of the bullet, and a relatively soft core engaging said jacket from said base and terminating short of said aperture to define a hollow point in said nose, said jacket at the nose being folded inwardly to form a plurality of jacket staves each abutting adjacent staves around said hollow point and aperture and to form intervening re-entrant folds defining jacket ribs extending inwardly into contiguity with adjacent ribs in said hollow point and radially subdividing said aperture into a multiplicity of hollows.

References Cited in the file of this patent UNITED STATES PATENTS 290,370 Thorn Dec. 18, 1883 2,045,964 Rinkel June 30, 1936 2,303,449 Fleischniann Dec. 1, 1942 2,333,091 Crasnotf Nov. 2, 1943 2,409,307 Patch et al. Oct. 15, 1946 2,444,722 Bogoslowsky July 6, 1948 2,792,618 Walker May 21, 1957 2,838,000 Schreiber -a June 10, 1958 2,986,091 Ferguson May 30, 1961 3,003,420 Nosler Oct. 10, 1961 3,069,748 Nosler Dec. 25, 1962 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,157 137 November 1% 1964 Arthur l'lqv Bulrns Jr.

rs in the above numbered pat- It is hereby certified that error appea Patent should read as ent requiring correction and that the said Letters corrected below.

Column 6, line 66, strike out comprisingh Signed and sealed this 6th day of April 1965,

(SEAL) Attest:

EDWARD J. BRENNER ERNEST W. SWIDER Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 3, 157 137 November 17 1964 Arthur H Burns Jr.

numbered patthat error appears in the above d as It is hereby certified.

that the said Letters Patent should rea ent requiring correction and corrected below.

Column 6, line 66 strike out "comprisingfl Signed and sealed this 6th day of April 1965.

(SEAL) Attest:

EDWARD J. BRENNER ERNEST W. SWIDER Attesting Officer Commissioner of Patents 

10. IN AN EXPANDING BULLET, THE COMBINATION COMPRISING A RELATIVELY HARD JACKET WITH A CLOSED BASE AND WITH A NOSE TAPERING TO A PARTITIONED APERTURE AT THE POINT OF THE BULLET, AND A RELATIVELY SOFT CORE ENGAGING SAID JACKET FROM SAID BASE AND TERMINATING SHORT OF SAID APERTURE TO DEFINE A HOLLOW POINT IN SAID NOSE, SAID JACKET AT THE NOSE BEING FOLDED INWARDLY TO FORM A PLURALITY OF JACKET SAVERS EACH ABUTTING ADJACENT STAVES AROUND SAID HOLLOW POINT 